It is probably not a clear-cut issue I suspect and you can read, should you wish, the replies thus far on the link above. I just thought it was something worth opening up to wider debate.

I do have his permission to repost here.

Levi's opening comment: 10 August 2012:

I see a looming problem in future research efforts that are trying to establish a diagnostic capability for ME/CFS based on PEM (post exertional malaise). Existing versions of the term include BOTH physical and mental versions of the term when referring to exertion. The problem I see is that all of the research is going into the physical side of the equation, none into the mental fatigue aspect of patient experiences. Both are measurable scientifically, however I have seen no studies combining the two types of PEM.

PEM is usually introduced into a subject's medical history via subjective patient experience; in other words, the patient either answers a questionnaire or tells a medical provider about the problem. Fatigue lab testing or neuro-psychiatric testing for both physical and mental PEM respectively is expensive and esoteric. However, PEM is shaping up to be the "Hallmark Symptom" of ME/CFS by researchers, apparently with the full support of the patient community. It would behoove us to clear up any confusion about the term sooner than later. What is your opinion about use of the term PEM?

Well physical and mental exhaustion are both caused by decreased ATP production, no? Not producing enough energy on demand. My simplified answer of course

I certainly would never tell a doctor that is unfamiliar with the pathology of ME that I have PEM. Un malaise means a "discomfort". You can have "un malaise" watching someone on t.v doing something embarrassing or inappropriate

I think one of my later comments on the other forum was that whilst it seems from my own perspective that physical and mental exertion should be separated - it is perfectly reasonable to believe that at some point in the future it will be determined that an underlying mechanism is responsible for both - or at least is capable of influencing both.

Firestorm, I agree with you. I guess we can speak from our own experiences too. For me, I didnt' have mental exhaustion/equilibrium difficulty/speech problems/nausea/unable to stand upright etc etc (PEM)after reading, preparing tax forms, concentrating etc for the first 10yrs of my illness. It was AFTER the 10yr mark when my health improved that I started to exercise a little and became more active physically that I starting experiencing this horrible "PEM" both physically and mentally. It appears as though the increase in physical activity affected my mental energy. Now both the mental and physical are affected and interchangeable; do too much physically it affects my brain, do too much concentrating then it affects my leg muscles and physical being.
Ok, what I just wrote seems to imply they are both related lol Funny how my minds works when I actually write it down. I'll go vote on your poll now )

I have always felt that the big problem with ME and such conditions is that they are firmly in the disputed region between mental and physical and that instead of that being acknowledged and studied we become part of the turf-war. Personally I find the distinction an anachronism but such is the inertia within medicine that's not going to change anytime soon.
Any studies will come at it from one side or the other, but for me the symptoms are so intertwined that I think they should be studied together. This is such an opportunity to forge a new understanding of how we work there have to be smart doctors out there willing to take up the challenge. Unfortunately, living in the UK, it won't be happening here.

My doc can't even acknowledge that I have CFS so what chance talking about PEM.

I think one of my later comments on the other forum was that whilst it seems from my own perspective that physical and mental exertion should be separated - it is perfectly reasonable to believe that at some point in the future it will be determined that an underlying mechanism is responsible for both - or at least is capable of influencing both.

Oh right. Good question. Here is what I said on the other forum. I'm not saying it will help mind, because, well, you'll see:

Ok. I think that not enough is known about PEM to be honest, and what is and what isn't being researched, focuses solely on Physical after effects of exertion e.g. focusing on muscle responses etc.

I think of mental PEM as being cognitive dysfunction. And that dysfunction (or 'fog') is exacerbated by mental exertion. However, it is there whether or not I am especially exerting myself mentally - if you follow me.

So that's how I separate the 'two'. I don't see that the mechanisms involved (that we know of) with muscular function before during and after exercise - can be the same as the mental ones.

UNLESS you take the search beyond muscles or mitochondria or whatnot. Say, hypothetically, research definitively establishes that neurological inflammation is involved - demonstrably so - in our condition.

Well, then I would imagine this might impact on cognitive ability AND it could impact on mobility and recovery from physical exercise - or exercise in general.

So... how to answer your survey? I think I will plumb for separate study for each

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And then,

If, at some point in the future, immunological dysfunction is found to be significant, then I suspect that could impact both on 'mental' and 'physical' exertion - or would have the potential to.

But, yeah, I tend to think in separate terms when considering my 'mental' and 'physical' disability and I don't think the two are necessarily caused by similar things in relation to PEM specifically.

Proof I suppose is that if I exercise beyond my limit, I suffer physically, not mentally. What I mean is I can overdo it physically, and still have cognitive/mental function. I can for example, read, or function in that way.

Except of course, that the fatigue induced by physical exercise tends to mean I can't do any mental activity for very long because of a need to sleep and/or rest.

Hmm... have I contradicted myself?

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So I think it isn't necessarily straightforward, but at present it is based on subjective patient reporting of symptoms and on that basis I think you can separate the two. Should science prove e.g. the central nervous system or immune system are abnormal it might prove these abnormalities do affect both mental and physical responses to exertion/exercise.

And if that doesn't make sense. I'll try again tomorrow. Only my vision is blurred now and I'm not thinking clearly. Mental PEM you see

For me, they're connected. Mental exertion can make me mentally and physically exhausted (and lead to PENE). Physical exertion can make me mentally and physically exhausted (and lead to PENE). It seems to me to be all the same failure of the energy system.

PENE/PEM are likely to have the same mechanism for mental and physical function, though this is not certain. However the impact will be different on the brain than on the muscles or heart. For this reason alone we should be looking wider in the research. A simple mind/body dichotomy wont do it though - I suspect we need to research this organ by organ.

The organs with highest energy demand are heart and brain. They should at least be investigated separately. I do not recall the other organ systems, though I would be very interested in both liver and gastrointesintal function during PEM.

Firsestorm, I think you did contradict yourself.. I agree the symptoms that people are describing can be subjective, but PENE is distinctive for those who actually experience it.

The mitochondria are our energy factories, this is where ATP is produced. They are found inside the brain where they do their hardest work. The brain consumes around 20% of the bodies O2 and half of our sugars we get from our diet. The brain is unable to store ATP and the mito are unable to share ATP from other mito in other organs.
So, if the mito in our brain stop producing ATP, the ATP produced by the mito in our heart can not help out.

My doctor explained to me that if we cause too much oxidative stress from exericisng etc, it can permanantly damage the mito DNA and once damaged that cell no longer produces energy.

I think mental PEM is distinct from brain fog. Mental PEM is the painful physical sensations that are similar to those for the body, but they occur in the head. Headaches, a sense of overworked muscles, weakness. It is tied to brain fog, but brain fog seems to be there before during and after exertion, while for me mental PEM starts either on initiating mental activity, or on good days, after I have been able to do a small amount of mental activity. It is allied to physical sensations much more than brain fog is. It prevents continuing function, due to the exhaustion. It may trigger differently and require different treatment than physical PEM but I think it is basically caused by the same things. Brain fog seems a somewhat different category of symptom.

I don't see that the mechanisms involved (that we know of) with muscular function before during and after exercise - can be the same as the mental ones. UNLESS you take the search beyond muscles or mitochondria or whatnot.

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You do not need to take the search beyond the mitochondria. Mitochondria provide energy for the brain the same as they do for the muscles. When I was an undergraduate, a medical student on my dorm floor told us that a person who is seriously studying is using as much energy as a person who is power walking or jogging.

I have always felt that the big problem with ME and such conditions is that they are firmly in the disputed region between mental and physical and that instead of that being acknowledged and studied we become part of the turf-war.

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I think the dispute could be extended to what is mental. Is it psychological issues or is neurological and cognitive function issues.

For me working my brain will cause brain PEM (not necessarily other kinds of PEM thou occassionally it does) but being physical can cause me PENE (including to my brain. my brain in this case thou may be having an after effect to the POTS).

I personally think we know enough already to know that this symptoms is probably to do with the mitochondria. I'd just like to know more on the whys? and how do we fix the mito issue causing these symptoms?. Why arent our mito working right? So seeing the same thing with mito is probably going on whether its in our brain or elsewhere.. maybe they shouldnt be separated??

Maybe thou people who dont get PEM in both the brain and elsewhere..should be a group which should be studied separate? as mito are everywhere in the body, so with mito issue one would expect that both forms of PEM to happen at times.

Mij's post thou was very interesting being that brain PEM didnt happen for him/her the first 10 years. I dont know if mito issues would fit with that description or not.

So for the past week the only exertion I have really engaged in has been mental. By that I mean I haven't pushed things physically by e.g. trying to go for a walk with my dog, which would usually result in purely physical payback.

See, I can sit here working away, and push beyond by comfort zone, and suffer purely mental effects. No muscles are affected. Yes I am shattered, but mentally so, and take last night, it is the neurological symptoms that flare and feel depleted the following day.

Now if I was to go beyond my physical exercise comfort zone, and incur payback, the symptoms are largely relating to muscle. And it is largely muscular problems I have the following day.

I mean I'm exhausted or fatigued all the time, but specific exertion results in specific (in the main) and distinct consequences. Of course it isn't always realistic to exert oneself solely through mental or solely physical activity.

But as I said I haven't discounted the notion that something connects it all, and yes, mitochondria would be one of the things I guess that if treated successfully could result in improvements all round in terms of PEM.

I see a looming problem in future research efforts that are trying to establish a diagnostic capability for ME/CFS based on PEM (post exertional malaise). Existing versions of the term include BOTH physical and mental versions of the term when referring to exertion. The problem I see is that all of the research is going into the physical side of the equation, none into the mental fatigue aspect of patient experiences. Both are measurable scientifically, however I have seen no studies combining the two types of PEM.

Click to expand...

Do studies involving mitochondria tend to report in terms of muscle fatigue/muscle energy for example?

When I was first ill I used to find I got bouts of symptoms in different body systems or parts.
Sometimes it would be my brain, but other times my legs, sometimes it would be my chest and neck - that was awful - breathing was really hard - I had to remember to do it and I couldn't hold my head up, sometimes it would be my digestive system.
The brain is just part of the body, and very often it's the bit that goes.
I'm absolutely convinced it's mitochondrial.
I'm still on the fence about whether mental and physical should be studied seperately.
Each exerts completely different problems on us and how we cope, but the root cause is the same.

It appears there is also decreased blood flow to the brain in ME. I would love to know why. I don't know if this is the case for me since I was never tested, but it sure feels like. Mito needs O2 in order to manufacture ATP, so without adequate bloodflow to our brain less energy is produced.

I think perhaps any confusion or concern arises because as a diagnostic symptom (something you have to have in order to get a diagnosis), PEM relates to any exertion response.

What I think Levi and certainly me were wondering is if this symptom can/should be researched as a collective entity or sub-divided perhaps into looking at 'mental' and 'physical' responses/abnormalities.